Existing audience converted to customers, then referred others.

Justin describes the August 2018 Product Hunt launch as going well because of years of prior community investment, not the launch mechanics themselves. No public ranking or signup count is given in any founder-authored or founder-interview source found.

People who had followed Justin's public journey for years actively rooted for the launch.

Direct, personal asks to podcaster friends to switch hosting providers and mention Transistor to their own audiences.

A friend running an affiliate-management company (Reward Full) became one of Transistor's first affiliates; a 25%-of-revenue-ongoing affiliate program followed, then podcast guest appearances in the affiliate niche drove more affiliate signups.

SEO investment is mentioned as one of several channels layered on as the affiliate/partner flywheel grew (affiliate review sites already ranked well for podcasting search terms).

Justin states plainly that paid ads have not worked for Transistor, in contrast to the other channels they kept reinvesting in.